Cold start issue

OldFoggey · #1 (**permalink**) 11-17-2012, 10:24 AM

Recently purchased Backdraft build # 889 and I've had an issue starting it from the time I got it home. The car is in excellent shape with only 1400 miles on it. When I went to look at the car I noticed every time the seller started it there was a black puff of smoke for an instant and the exhaust had a heavy fuel smell for a minute or so. The seller said he did have an issue with a small piece of trash in the front float needle but he removed it and everything was good after that. I figured that the float was just set a little high and was causing the issue at start up. After I got the car home I checked the float levels and the front was a little high. I adjusted it to specs but that seemed to fix the initial rich mixture and also smoothed out the idle after I adjusted it. I guess the problem is that it's been too long since owning a vehicle with a carb because most of the time I flood it when trying to get it started. I then get disgusted, throw the cover back over it and walk away. I read that the Edelbrock Victor Jr manifold has a low vacuum at idle so I thought maybe a different carb with idle adjustments at all four corners would help. I replaced the Holley with a 750cmf Quick Fuel Hot Rod model. I fought the thing for a couple days and it finally fired up. I adjusted the float levels which were almost spot on from the factory and adjusted all 4 mixture screws using a vacuum gauge to achieve 16 - 17 lbs vacuum. The car idles beautifully and no fuel smell to the exhaust. But still same issue if the car sits for a couple days. I have tried not pumping the gas, pumping it once, pumping it 1/2 pump all to no avail. After a minute or so of it turning over there's a strong small of gas. I put in a new set of spark plugs, used a spark checker and the MSD 6 ignition passes all the tests shown on their web site. Once when I did have it running I checked the spark advance and it's set right at 12 initial and 32 full. The engine is the 351W punched to 392ci from Ford Racing. I retired from the military after 22 years back in 1987 and was planning on fully retiring in the near future. This was the car of my dreams and my old age crisis toy but it's got to the point I'm ready to unload it. I've found posts on hot starting issues but not when cold. Oh, by the way, when I replaced the carb and it didn't start right away I made a one second spray of starting fluid over the carb barrels, not in the carb, just to make sure there wasn't a spark issue that I missed and it fired right up. Anyone have any ideas to toss my way?

Grubby · #2 (**permalink**) 11-17-2012, 10:55 AM

Do you have a choke? Electric or Manual?

I know the QF HR has a choke, but you may not be using it.

John

CHANMADD · #3 (**permalink**) 11-17-2012, 10:55 AM

Try, borrow or get somehow a normal ignition ....ie coil and distributer....in other words bypass the MSD, and see if you have any luck...also make sure that your ignition switch is allowing current to pass to the ignition when you are cranking.......it could be the ignition switch...

vector1 · #4 (**permalink**) 11-17-2012, 11:43 AM

how does it run when it is hot or at operating temp?

Gaz64 · #5 (**permalink**) 11-17-2012, 01:29 PM

Check your float levels are still correct PRIOR to the next cold start.

If you're running a mechanical fuel pump, and your carb fuel is evaporating after hot shutdown, then you'll suffer on the next cold start.

Have you got the throttle open when trying to start?

Consider getting the choke to work correctly.

If you can get 15-17 inches of vacuum, the motor must be fairly mild.

My mates solid roller 355, single plane manifold, QFT 750 and MSD 6AL fires up with a half pedal pump AND idles within 30 seconds.

jhv48 · #6 (**permalink**) 11-17-2012, 04:04 PM

Might just be me, but 12 degrees initial timing is not that much. I would try a few more degrees and see if that helps. I run 15 degrees and one pump fires it right up with no choke.

vector1 · #7 (**permalink**) 11-17-2012, 06:21 PM

if it runs good when hot you can make a small adjustment.

make sure all the adjustments are out the same amount, then turn them all out another 1/8 of a turn and see how it runs, both on startup and at temp. when you adjust your carb with it hot using the vacuum gauge it has been my experience you can end up too lean for best all around performance. you can keep making adjustments like this til you find something you like.

OldFoggey · #8 (**permalink**) 11-17-2012, 08:54 PM

The Quick Fuel carb has an electric choke and is a double pumper like the Holley I took off. The choke kicks in as soon as I move the throttle so it's working. The good thing about the Quick Fuel carb is there's site glasses on the float bowls and there's fuel in there from the start. I have got the thing to start a couple times but I have no idea what I did different those times. It just seems logical to me anyway, that once I smell fuel it's flooded. The car runs absolutely great once I get it started. I really don't think it's a problem with the MSD ignition. I pulled each plug wire and hooked it into a spark checked and had a brilliant blue spark at each plug. I'm thinking that it's a problem with the manifold being a single plane and not enough vacuum at the rpm the starter turns it over to vaporize the fuel. Almost to the point that if I can't get it started in August and September when it's 90 degrees I'd be afraid to take it somewhere and park it when it gets down in the 50's.

Thanks for all of the replies.....Don

tcrist · #9 (**permalink**) 11-17-2012, 09:25 PM

I did not see where you mentioned if you have a fuel pressure regulator. I would get a fuel pressure regulator and set it at 5-7 PSI see if that helps. Sure can't hurt to have one on it anyway.

OldFoggey · #10 (**permalink**) 11-18-2012, 08:51 AM

It has the mechanical fuel pump that it came with in the crate. I'd have to go dig out the tuning paperwork from Quick Fuel Technology but I think they recommended 7 lbs pressure to ensure adaquate volume at higher rpm. I don't have that problem because it runs terrific on the freeway it I ever get it started. I haven't contacted Quick Fuel support yet but will probably do that tomorrow.

Thanks again for all the suggestions.......Don

Rick Parker · #11 (**permalink**) 11-18-2012, 11:44 AM

What CFM rating is the carb? Disable the choke. Generally these cars with their High Performance engines do not require one unless in very cold climates. The open plenum Victor Jr manifold will not send a real strong signal to the carburetor boosters without a BIG cam so it may be a little finaky. When cold pump the throttle once or twice with the choke disabled and crank it, it should fire up. It is probably getting temprarily flooded. I ran a Victor Jr for years with a Barry Grant modified Double Pumper (choke body removed) never had any issues. Don't get discouraged. As mentioned be sure your ignition is good.